The present invention relates to an information processing system having a simplex system and a duplex system, and more particularly to a device for acquiring status data of the simplex system from a standby system in the duplex section.
An information processing system, such as an exchange system, has a duplex system and a simplex system. With such a configuration, supposing one of two systems of the duplex system to be a 0 system and the other to be a 1 system, a controller produces a signal (called an act signal) indicating which of the two systems is an act system (a system in use) or a standby system (a system on standby). The act signal is applied to various processing units so as to manage redundant configuration. The duplex system is equipped with a maintenance data acquisition section for each of the systems so as to accommodate switching between the act and standby systems.
FIG. 1 illustrates a block diagram of a prior art system. In this figure, 10 denotes a simplex system which is equipped with a line circuit such as a subscriber's line (or transmission line), 11 denotes the line circuit, 12 denotes a line data acquiring section or units which acquires and holds status data indicating the status of the simplex system, 13 denotes a first selector (SEL1) which switches the transmission line to the 0 system or the 1 system in a duplex system, 14 denotes a second selector (SEL2) which switches the line data acquiring section or unit 12 to either of management data acquiring units for the 0 and 1 systems, 15 denotes a controller which controls the selectors 13 and 14, and 16 to 19 denote sections or units constituting the duplex system. The sections or units 16 and 17 are 0- and 1-system line accommodating sections or units (including multiplexing/demultiplexing circuits) connected to the simplex system, and the units 18 and 19 are 0- and 1-system data acquiring or units, connected to the 0- and 1-system line accommodating or units, which acquire status data from corresponding line accommodating sections 16 and 17 and apply necessary data. Though not shown, a duplex switching system is similarly connected on the right side of the line accommodating or units 16 and 17.
In such an arrangement, upon receipt of an act (ACT0) signal at, for example, a low level from the 0-system data acquiring or units 18, the switching controller 15 generates a switching control signal to thereby switch the first and second selectors 13 and 14 to the 0 system. In response to an act (ACT1) signal at a low level from the 1-system data acquiring section or unit 19, on the other hand, the controller 15 switches the first and second selectors 13 and 14 to the 1 system.
In this system configuration, the act-system data acquiring section or unit and the standby-system data acquiring section or unit acquire status data from their respective corresponding line accommodating sections or units (16 or 17).
It should be noted that the term "section" used throughout the specification means a unit or circuit carrying out the respective function associated therewith as disclosed in the specification.
The act-system data acquiring section thus acquires various failure data and supplies them to software (another controller not shown) as deciding factors for the normality of the act system. As a result, the software makes a decision as to whether or not switching between the systems in the duplex system is needed. For this reason, the 0- and 1-system data acquiring sections 18 and 19 for acquiring failure data are respectively provided to correspond to the 0 and 1 systems.
The act-system data acquiring section (18 or 19) in the duplex system takes the status of the simplex system 10 out of the line data acquiring section 12 via the second selector 14 to thereby understand the status of the simplex system 10.
Supposing that, in the duplex system, the 0 system is operating as the act system and if this 0 system fails, immediate switching from the 0 system to the 1 system is required. In order to make this switching, a diagnosis must be made beforehand as to whether or not the standby system is in the normal state. After verification that the standby system is normal, it can be switched to a new act system whenever a failure occurs in the old act system. In order to make that diagnosis, it is necessary for the data acquiring section in the standby system to hold data indicating the current status of the data acquiring section in the simplex system.
Specifically, in order to make a diagnosis as to whether or not the standby line accommodating section (17 when the 1 system is on standby) in the duplex system can operate properly, it is necessary for the corresponding data acquiring section (19 when the 1 system is on standby) to acquire data from the line data acquiring section 12 in the simplex system 10.
With the prior art system, however, the switching control section 15 controls the selectors 13 and 14 so that they are continually connected to the act system, which does not permit the data acquiring section 18 (or 19) to acquire status data of the simplex system 10.
For this reason, heretofore, the system switching has been made without making a diagnosis of whether or not the standby system operates normally. With such system switching, in case where the standby system is faulty, both of the failing 0 and 1 systems will bring the system down immediately after the switching from the act system to the standby system.